Spacewalkers to test shuttle heat shield repair

Astronauts aboard the International Space Station are preparing for a spacewalk on Thursday to test a heat shield repair technique and replace a failed circuit breaker.

It will be the fourth of five spacewalks scheduled during space shuttle Endeavour’s busy 12-day visit to the orbital outpost for construction and repair work.

“It will be a very ambitious day. It’s a day that we’ve been waiting for for a while,” shuttle flight director Mike Moses said at the Johnson Space Center in Houston late on Wednesday.

The heat shield test had been planned on a previous shuttle mission, but had to be shelved for more urgent tasks.

Advertisement

Astronauts Robert Behnken and Mike Foreman will “camp out” during their sleep period in the station’s Quest airlock to purge nitrogen from their bodies ahead of the spacewalk, which was set to start at 2228 GMT on Thursday.

The repair technique to be tested on the spacewalk will be conducted on experimental heat shield tiles that have been intentionally damaged.

Caulk gun

NASA wants to do the test before sending a shuttle crew to fix the Hubble Space Telescope in a few months. Astronauts flying to Hubble won’t be able to reach the space station for shelter if their ship is too damaged to return to Earth.

NASA developed inspection and repair options after losing shuttle Columbia and its seven-member crew in 2003 due to undetected heat shield damage.

Thursday’s test will involve an instrument called a tile repair ablator dispenser, which is essentially a sophisticated caulk gun. It will dispense a gooey material to fill gouges in the damaged tiles.

Such damage could be inflicted during take-off. It is hoped the substance would protect the tiles during re-entry into the Earth’s atmosphere.

The sample tiles will be returned to Earth to undergo extensive testing on the ground.

The astronauts had much of Wednesday off, taking a much-needed break from their gruelling mission. The crew has already assembled a Canadian-built robotic maintenance man on a trip also used to deliver a storage room for Japan’s upcoming Kibo laboratory complex.

The Space Shuttle – Learn more in our continuously updated special report.